Cognitive impairment after traumatic brain injury is associated with reduced long-term depression of excitatory postsynaptic potential in the rat hippocampal dentate gyrus.

Traumatic brain injury can cause loss of neuronal tissue, remote symptomatic epilepsy, and cognitive deficits. However, the mechanisms underlying the effects of traumatic brain injury are not yet clear. Hippocampal excitability is strongly correlated with cognitive dysfunction and remote symptomatic epilepsy. In this study, we examined the relationship between traumatic brain injury-induced neuronal loss and subsequent hippocampal regional excitability. We used hydraulic percussion to generate a rat model of traumatic brain injury. At 7 days after injury, the mean modified neurological severity score was 9.5, suggesting that the neurological function of the rats was remarkably impaired. Electrophysiology and immunocytochemical staining revealed increases in the slope of excitatory postsynaptic potentials and long-term depression (indicating weakened long-term inhibition), and the numbers of cholecystokinin and parvalbumin immunoreactive cells were clearly reduced in the rat hippocampal dentate gyrus. These results indicate that interneuronal loss and changes in excitability occurred in the hippocampal dentate gyrus. Thus, traumatic brain injury-induced loss of interneurons appears to be associated with reduced long-term depression in the hippocampal dentate gyrus.

Utilisation of adsorption and desorption for simultaneously improving protein crystallisation success rate and crystal quality.

High-quality protein crystals of suitable size are an important prerequisite for applying X-ray crystallography to determine the 3-dimensional structure of proteins. However, it is often difficult to obtain protein crystals of appropriate size and quality because nucleation and growth processes can be unsuccessful. Here, we show that by adsorbing proteins onto porous polystyrene-divinylbenzene microspheres (SDB) floating on the surface of the crystallisation solution, a localised high supersaturation region at the surface of the microspheres and a low supersaturation region below the microspheres can coexist in a single solution. The crystals will easily nucleate in the region of high supersaturation, but when they grow to a certain size, they will sediment to the region of low supersaturation and continue to grow. In this way, the probability of crystallisation and crystal quality can be simultaneously increased in a single solution without changing other crystallisation parameters.

Effects of glucocorticoids on traumatic brain injury related critical illness-related corticosteroid insufficiency.

BACKGROUND: Traumatic brain injury (TBI) is a heterogeneous condition that can lead to critical LLLness-related corticosteroid insufficiency (CIRCI) causing a high mortality and morbidity. Glucocorticoids were widely used in the clinical management of TBI, but their benefit has been challenged in some studies and their efficacy, especially for treating CIRCI in TBI patients, remains unclear. METHODS: We conducted a meta-analysis of published data to determine if the controversy is related to clinical dosing and timing of glucocorticoids (GCs) application. We analyzed published reports in four databases (MEDLINE, EMBASE, the Cochrane Controlled Trials Register, and CBMdisc). The published data were stratified into not only low- and high-dose GCs group but also short- and long-term GCs group to compare their effectiveness in improving TBI outcomes. RESULTS: We totally identified 16 reports. For low-dose patients, the pooled relative risks (RRs) for two clinical outcomes of death or a combination of death and severe disability were 0.95 (95% confidence interval (CI): 0.80 to 1.13) and 0.95 (95% CI: 0.83 to 1.09), respectively. The risks for infection and gastrointestinal bleeding were 0.85 (95% CI: 0.50 to 1.45) and 0.64 (95% CI: 0.15 to 2.70), respectively. For high-dose group, the pooled RR of death is 1.14 (95% CI: 1.06 to 1.21). The pooled RRs for infection and gastrointestinal bleeding for the high-dose patients were 1.04 (95% CI: 0.93 to 1.15) and 1.26 (95% CI: 0.92 to 1.75), respectively. For long-term use group, the pooled RRs for two clinical outcomes of death or a combination of death and severe disability were 0.98 (95% CI: 0.87 to 1.12) and 1.00 (95% CI: 0.90 to 1.11), respectively. The risks for infection and gastrointestinal bleeding were 0.88 (95% CI: 0.71 to 1.11) and 0.96 (95% CI: 0.35 to 2.66), respectively. For short-term use group, the pooled RR of death is 1.15 (95% CI: 1.07 to 1.23), and importantly the effects on infections were beneficial in terms of TBI patients suffering from CIRCI. CONCLUSIONS: This meta-analysis suggests an increased risk of death for TBI patients on a high dose and short term of glucocorticoids compared with those on a low dose and long term, for whom a trend towards clinical improvement is evident. In addition, stress-does of GCs further decrease the pneumonia incidence in TBI patients suffering from CIRCI. A large-scale multicenter randomized controlled trial is warranted for testing (1) the efficacy of stress-dose GCs treatment in the sub-acute phase of TBI (4-21 days after initial trauma), when CIRCI is most likely to occur; (2) the hypothesis that stress-dose GCs could boost patients' stress function and ensure survival.

[Computational-fluid-dynamical analysis of the flow field of forearm flap with four types of venous anastomotic techniques].

PURPOSE: Using the computational fluid dynamics to analyse the alteration of flow field of free forearm flap with 4 different venous anastomotic techniques, and to preliminarily explore its clinical significance. METHODS: Three dimensional geometric models of radial forearm flap with 4 types of anastomotic techniques between radial vein and recipient vessels were established by Pro/E (Wildfire 4.0) as follow: type I(matched anastomosis), type II(stump anastomosis), type III (angular anastomosis) and type IV(end-to-side anastomosis). Then the established geometric models were transferred to the SC/Tetra 8.0 software for mesh generation and calculation. Porous model was applied to the flap to simulate capillary structure as before, inlet velocity of radial artery was set as 20mm/s and outlet pressure of recipient vein as 0 Pa. By comparing pressure and velocity distribution on different cross sections of blood vessels, hemodynamic feature of the flap with 4 types of anastomotic techniques was studied, focusing on the alternation of flow field of drainage system of the flap, especially at the anastomotic sites. The data was analysed using SAS8.0 software package for ANOVA. RESULTS: The pressure on the four sections of the flap circulatory system was significantly higher in type I compared with type II, III and IV (F=40.99,P<0.001). Type II presented with vortex in the anastomotic site, and type III,IV with smooth flow. Type IV had an absorption effect at the anastomotic site. The pressure loss of the flap circulation was maximal in the radial vein of vascular pedicle(F=97.00,P<0.001). CONCLUSIONS: Type III and IV are considered appropriate techniques to deal with caliber discrepancy of recipient site. Theoretically, reasonable reduction of the vascular pedicle length and choice of the concomitant radial vein with wider radius for anastomosis can effectively decrease the resistance of circulation in the flap.

[Chronic effects of oligomeric Aß(1-42) on hippocampal synaptic plasticity in vivo].

Synaptic plasticity, including long-term potentiation (LTP) and long-term depression (LTD), is widely considered as one of the major mechanisms underlying learning and memory. This study explored hippocampal synaptic plasticity and spatial memory formation of an Alzheimer's disease (AD) rat model established by intrahippocampal injection of oligomeric Aß(1-42). Twenty four Sprague-Dawley rats at 2.5 months of age were randomly divided into AD and control groups, and were bilaterally injected with 5 µg oligomeric Aß(1-42) or normal saline into dentate gyrus (DG) of hippocampus. Morris water maze test was used to observe the capability of learning and memory of two groups, 30 d after injection. To investigate the variations of paired-pulse facilitation (PPF) and range of synaptic plasticity, field potentials were recorded in the DG of the dorsal hippocampus by stimulating the perforant path (PP). The results showed that oligomeric Aß(1-42) obviously impaired spatial memory formation in rats (P < 0.05). Furthermore, oligomeric Aß(1-42) reduced the PPF ratio (P < 0.05) and hippocampal LTP formation (P < 0.05), while facilitated the hippocampal LTD formation (P < 0.05). These data suggest that chronic Aß aggregation impairs synaptic plasticity of hippocampal PP-DG pathway, which may be involved in the spatial memory deficit in AD rats.

[Establishment of hemodynamic model of human radial forearm free flap].

PURPOSE: To preliminarily establish a hemodynamic 3D numeric model of radial forearm free flap with vascular pedicle of radial artery and vein, and discuss its scientific workability. METHODS: The 3D geometric model of 50mm×80mm×10mm radial forearm flap was established by Pro/E(Wildfire 4.0). The vascular pedicle was 50mm in length including radial artery (inside diameter was 1.9mm) and concomitant radial vein (inside diameter was 0.84mm). The half-embedded vessels went hrough the flap paralleling the long axis. Then the established geometric model was transferred to the SC/Tetra 8.0 software for mesh generation and calculation. According to the virtual flow volume of the radial artery, the inlet velocity was set as 20mm/s. With the different blood pressure of 53mmHg between the feeding artery and draining vein, the tentative porous values were achieved. Then porous model was applied to the flap to simulate the capillary structure. The pressure distribution on the central axis of radial artery and vein and the radial velocity distribution in three different cross sections of vessels were figured out. RESULTS: A model with 10355473 meshes and 2104014 nodes was built. When porous model was applied, the pressure difference between radial artery and vein was calculated to 7050 Pa (52.8mmHg), which was close to clinical value. The computational fluid dynamic analysis results showed that with porous model, the central pressure of radial artery was continuously kept to a higher level. When blood flowed in and flows out of the flap, the blood velocity decreased and increased greatly. While the central pressure of radial vein significantly decreased at the moment of blood flowing out of the flap. These results basically agreed with the features of normal blood circulation of the forearm flap. CONCLUSIONS: Porous model effectively simulates hemodynamic status of forearm flap, which provides a new method for the study of mechanism of blood circulation in radial forearm flap and also lays a foundation for the following hemodynamic study of vascular anastomosis.

Traumatic brain injury impairs synaptic plasticity in hippocampus in rats.

BACKGROUND: Traumatic brain injury (TBI) often causes cognitive deficits and remote symptomatic epilepsy. Hippocampal regional excitability is associated with the cognitive function. However, little is known about injury-induced neuronal loss and subsequent alterations of hippocampal regional excitability. The present study was designed to determine whether TBI may impair the cellular circuit in the hippocampus. METHODS: Forty male Wistar rats were randomized into control (n = 20) and TBI groups (n = 20). Long-term potentiation, extracellular input/output curves, and hippocampal parvalbumin-immunoreactive and cholecystokinin-immunoreactive interneurons were compared between the two groups. RESULTS: TBI resulted in a significantly increased excitability in the dentate gyrus (DG), but a significantly decreased excitability in the cornu ammonis 1 (CA1) area. Using design-based stereological injury procedures, we induced interneuronal loss in the DG and CA3 subregions in the hippocampus, but not in the CA1 area. CONCLUSIONS: TBI leads to the impairment of hippocampus synaptic plasticity due to the changing of interneuronal interaction. The injury-induced disruption of synaptic efficacy within the hippocampal circuit may underlie the observed cognitive deficits and symptomatic epilepsy.

[Effect of low-intensity pulsed ultrasound on the enchondral bone formation in posterolateral lumbar fusion in rabbits].

OBJECTIVE: To observe the effect of daily low-intensity pulsed ultrasound (LIPUs) therapy on improving the enchondral bone formation in lumbar fusion in rabbit models, and to explore its possible mechanism. METHODS: Posterolateral noninstrumented bilateral fusions were performed at the L5 approximately L6 levels in 20 New Zealand rabbits. The autograft iliac bone was implanted on the left side, and the hydroxyapatite bioceramic artificial bone on the right. The rabbits were divided into a treatment group and a control group randomly. One week after the surgery, LIUPs was administered for 20 minutes per day for 4 weeks over the fusion site in the treatment group and false treatment was used in the control group. Post-anterior X-ray photographs were taken to determine the conditions of fusion area, and then, rabbits were killed and the fusion tissues were obtained. Chondrocytes were detected by histological and cytological methods. RESULTS: Compared with the control group, the fusion rate of the treatment group was significantly up-regulated (P<0.05). There was plenty bone trabecula in the fusion area in the treatment group, the number of chondrocytes was also higher than that of the control group (P<0.05), and there was no statistical difference in the number of chondrocytes between the iliac and artificial bone tissues after the treatment(P>0.05). CONCLUSION: Low-intensity pulsed ultrasound therapy improves the endochondral bone formation in the lumbar spine fusion in rabbit models.